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Precursor Ink Engineering of Perovskite for Enhanced Stability and Performance in Carbon-Based Perovskite Solar Cells

Ghayoor, Reza | 2025

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58537 (46)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Taghavinia, Nima; Mohammadpour, Raheleh; Tajabadi, Fariba
  7. Abstract:
  8. Perovskite solar cells (PSCs) have emerged as a leading thin-film photovoltaic technology owing to their outstanding optoelectronic properties, low fabrication cost, and compatibility with flexible substrates. However, the intrinsic instability of methylammonium (MA)–containing compositions remains a major barrier to commercialization; therefore, developing stable MA-free inks is essential for achieving efficient and durable devices. This dissertation presents an integrated strategy for improving the performance and stability of formamidinium-based, MA-free PSCs with carbon electrodes, built on three pillars: ink-formulation engineering, crystallization control, and interfacial modification. Incorporating 4 wt% ammonium formate (AF) into the MA-free ink extended solution stability to >20 days, suppressed residual impurity phases, and enabled the formation of uniform, dense, pinhole-free films. Devices fabricated from the AF-optimized ink delivered a 19.40% PCE and maintained their performance for >1000 h under ISOS-D1 ambient conditions (25 °C, RH ≈ 50%). To further stabilize the surface and mitigate recombination, hexadecylamine (HDA) was employed as a post-deposition surface treatment. The long-chain amine increased the water contact angle from 51° to 87°, enhanced charge separation as reflected by an increase in the time-resolved photoluminescence average lifetime (τavg from 135 ns to 336 ns), and enabled devices to retain >95% of their initial efficiency after 6000 h under ambient conditions (25 °C, RH ≈ 50%) without encapsulation. Finally, a multifunctional additive, AMPS, was introduced to improve crystal quality and suppress structural defects. AMPS facilitated more uniform crystal growth, extended carrier lifetimes (τavg from 297 ns to 450 ns), and interacted with under-coordinated Pb via Pb–O coordination, thereby modulating crystallization and reducing electronic defects. As a result, carbon-electrode devices achieved a 20.23% PCE, comparable to state-of-the-art values for this device architecture. Overall, this work proposes practical routes for defect management and crystallization control in MA-free inks and introduces functionally complementary surface and ink additives, paving the way for stable, cost-effective, and scalable perovskite photovoltaics
  9. Keywords:
  10. Carbon-Based Perovskite Solar Cells (PSCs) ; Defect and Crystallization Engineering ; Methyl Ammonium (MA) Free Perovskite ; Perovskite-Based Solar Cell ; High Efficiency Carbon-Based Perovskite Solar Cells (PSCs)

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